The movement and efficiency of applied phosphorus to rice (Oryza sativa L.) in flooded soil

Abstract

Soil solution phosphorus (P) concentration and proportions of the total soil solution P originating from applied fertilizer were monitored at 4 day intervals throughout the vegetative growth period of rice (Oryza sativa L. cultivar 'Bluebelle'). Two soils from the Gulf Coast region of Texas were used. Both soils were classified as Crowley fsl but one had been recently leveled removing approximately 10 cm of topsoil (Crowley cut). Four P-³²P treatments were used: 0 ppm P with 0.0 uCi³²P, 25 ppm P with 37.5 uCi³²P, 50 ppm P with 75.0 uCi³²P, and 100 ppm P with 150 uCi³²P, respectively. Almost 100% of the soil solution P originated from fertilizer P on the Crowley (cut) fsl which had a total soil P concentration of 63 ppm with that of the normal Crowley fsl soil being less than 100%. In the one case in the greenhouse when the soil solution P concentration was less than 0.1 ppm an increase in yield 1 was obtained when P fertilizer was applied. Total plant P and proportion of plant P originating from fertilizer P were determined at 2 week intervals throughout the vegetative growth period of rice. A significant increase in total plant P and the proportion of plant P originating from fertilizer P was obtained from the Crowley (cut) fsl but not from the normal Crowley fsl soil. Fertilizer efficiencies were higher on the soil with the lowest total P concentration, the Crowley (cut) fsl soil. Fertilizer efficiencies ranged from a low of 1% on the normal Crowley fsl soil to a high of 17% on the Crowley (cut) fsl soil and were inversely proportional to the level of P treatment. ...